Bioactive compositions, such as pharmaceuticals, provide effective treatments for a variety of illnesses. Unfortunately, administration of therapeutically effective doses of many medications can be difficult in some instances. For example, some drugs (particularly peptide based drugs, such as insulin) are partially or totally inactivated by the highly acidic environment of the stomach if orally ingested. Another problem is the “first pass” effect, which refers to the partial inactivation of orally ingested drugs in the liver after they have been absorbed from the gastrointestinal system and before they have exerted their full therapeutic effect. In addition to such physiological obstacles to administration, patients often fail to take their medications at the proper prescribed intervals or for the necessary period of time.
In addition to oral ingestion, inhalational administration has been used as an alternative route of drug delivery. Inhaled drugs can be absorbed directly through the mucous membranes and epithelium of the respiratory tract, thereby minimizing initial inactivation of bioactive substances by the liver. Inhalational delivery also can provide drugs directly to therapeutic sites of action (such as the lungs or the sinuses). This mode of administration has been particularly effective for the delivery of pulmonary drugs (such as asthma medications) and peptide based drugs (usually via intranasal administration), using metered dose inhalers (MDIs). However, MDIs often require coordinating inhalation with actuation of the MDI, and some patients are not able to master this technique. Moreover, patients often forget to take medications at prescribed times or with the prescribed frequency, and some patients inadvertently or inappropriately use medications, leading to hospitalizations, permanent injury, and even death.